After reading the title of this thread and googling "WTF is the superman curse", followed by several minutes of intensive research I can say with 100% certianty that the superman curse is indeed a real thing.

It is caused by a WW2 era bar of unexploded kryptonite that is still orbiting the moon where the original superman threw it in the process of foiling a nazi plot. The kryptonite is sealed in a lead-lined diamond container that has the kal-el family seal etched into the diamond.

As a result whenever some Hollywood pretty-boy puts on a lycra suit with the <S> on the front of it, the deadly kryptonite starts to vibrate in sync with it and the diamond container causes it to form a deadly death ray. The exact effects of this deadly death ray can vary but will often include various forms of deadly death, like falling off a horse or getting Alzheimer's disease and dying aged 88.

Make no mistake, this is a very serious curse - think twice before wearing your undies outside your tights!